The Best Preamp is no Preamp?

Thus, the only explanation for this is that the brain “likes” certain types and amounts of distortion. A more complex topic is how distortion from different parts of the chain interact.

@tangramca There is more than one explanation! If you've ever heard differences between interconnect cables then you know that they can color the sound too. A good linestage can vastly reduce this coloration (on account of its lower output impedance). If the linestage is doing its job properly you might not hear any significant difference between interconnect cables at all.

I suppose integrates could have a say in this? Thanks 

Sorry, integrated amps 

I have owned many preamps most all types as well as integrated etc. And it's about synergy some systems just sound better with active over passive or direct. You can get more impact dynamics and overall better sound quality if your system requires an active over passive. At this time I tend to prefer tube preamplification over my solid-state or passives or direct DAC to the amp. But as I mentioned it depends on the system after all we listen to systems, not components.

If you have a strong enough signal to drive a power amp, why add more electronics? You need some way to switch sources and a volume control. Active electronics are not necessary, and, as you have discovered, can only make things worse! Good for you! My testing, evaluating, and office/lab/workroom system has no pre-amp. Don't spend money on what you don't need!